1. Technical Field
This invention relates to high energy laser apparatus and more particularly to structures for shielding the environment of the laser gain module against the nonlasing radiation that accompanies the generation of the high intensity, high energy laser beam.
2. Discussion
High energy laser systems have demonstrated utility in industrial applications, having been successfully applied in a wide range of manufacturing and production operations ranging from welding automobile body frames to drilling small holes in metal The laser systems are reliable and perform tasks rapidly and with precision.
In testing a new high energy laser system particular attention should be given to the heat generated in the environment of the laser gain module. Applicant has found that the generation of a high energy laser beam is typically accompanied by a significant amount of heat generated due to the nonlasing radiation. Applicant has further determined that a large proportion of the heat put out by the apparatus finds itself in the nonlasing radiation. By applicant's estimate only 30% of the radiation that is generated by the gain module ends up in the form of the high intensity laser beam and the remainder goes into nonlasing radiation. The nonlasing radiation tends to heat up the operating environment in the immediate vicinity of the gain module which results in an adverse effect on the performance of the apparatus.
A brief explanation of the construction and operation of the high energy laser system may be helpful to better understand the basis for the need to provide shielding structures that control the temperature levels in the operating environment of the gain module. A high energy laser apparatus will generally comprise a solid state laser source comprising a zig-zag slab amplifier positioned between resonator mirrors. The beam is amplified from the zig-zag slab reflecting the light beam back and forth through the slab amplifier. The amplified beam is extracted from the slab in the form of a high quality, high brightness beam with an average beam power of 100 watts to 5000 watts or more. The apparatus generates a great deal of heat not only in the form of the high intensity laser beam but from the arrays of laser diodes that excite the laser slab medium. The nonlaser heat energy if not removed heats up the operating environment of the slab amplifier and the immediate space surrounding the gain module raising the temperature of the space through which the high intensity beam must pass in order to reach its designated working site.
As is well known the quality of the laser beam is affected by the changes in the refractive index of the atmosphere air through which it is generated or otherwise must pass. As the space surrounding the laser gain module heats up due to the nonlasing heat it changes the refractive index of the ambient air. Wide variations in temperature will cause variations in the refractive index of the air through which the high intensity beam must pass. This condition is known to degrade the beam quality.
Rising temperatures in and around the gain module will result in other deleterious effects on the optics and other instruments that respond adversely to thermal expansion. Accordingly, the critically aligned optical system, including the reflective surfaces will distort making it difficult to focus the high intensity beam or point it to the work site. There is a significant need to control and contain the temperature level within and around the gain module to produce an appropriately high quality laser beam that can be used in commercial applications.